As an example, in a motor control inverter which handles high electric power, an IGBT (Insulated Gate Bipolar Transistor) has been widely used as a switching element. It is necessary to perform a communication of a control signal while maintaining high voltage insulation between a gate driver which drives an inverter and a logic part which outputs a driving control signal to the gate driver. As a method of transmitting a signal by electrically insulating between circuits of which reference potentials are different from each other, a method of using an insulating element such as photo coupler, or a transistor has been known. An insulating element based on a different coupling method such as optical coupling, magnetic coupling, or capacitance coupling has been known, however, for use with high electric power/high voltage, a method of performing communications of control signals using an optical module and an optical fiber with excellent insulating property is mainstream. An example of an inverter control system using an optical fiber is disclosed in PTL 1. In PTL 2, a communication system in which a small amount of electromagnetic wave is leaked is realized at low cost by connecting a wireless communicator to a sheet having a waveguide structure which is configured by a mesh layer, a conductor layer, and a dielectric layer, and receiving an electromagnetic wave which leaks from the mesh layer through an antenna.